This invention relates to electric power utility networks including generating systems, transmission systems, and distribution systems serving loads. In particular, the invention relates to controlling the transfer of energy to and from a utility power network. Energy storage devices, including capacitor banks and superconducting magnetic energy storage devices (SMES), are used to provide power to a utility power network in order to compensate for power shortfalls or voltage instability problems on the network. For example, in the event of a fault or outage on the network, power may be transferred from an energy storage device to the network to ensure that the amount of power on the network remains within acceptable limits.